RF MODULE

Microwave Cancer Therapy
Introduction
Electromagnetic heating appears in a wide range of engineering problems and is ideally
suited for modeling in COMSOL Multiphysics because of its multiphysics capabilities.
This example comes from the area of hyperthermic oncology and it models the
electromagnetic field coupled to the bioheat equation. The modeling issues and
techniques are generally applicable to any problem involving electromagnetic heating.
In hyperthermic oncology, cancer is treated by applying localized heating to the tumor
tissue, often in combination with chemotherapy or radiotherapy. Some of the
challenges associated with the selective heating of deep-seated tumors without
damaging surrounding tissue are:
Control of heating power and spatial distribution
Design and placement of temperature sensors
Among possible heating techniques, RF and microwave heating have attracted much
attention from clinical researchers. Microwave coagulation therapy is one such
technique where a thin microwave antenna is inserted into the tumor. The microwaves
heat up the tumor, producing a coagulated region where the cancer cells are killed.
This model computes the temperature field, the radiation field, and the specific
absorption rate (SAR)—defined as the ratio of absorbed heat power and tissue
density—in liver tissue when using a thin coaxial slot antenna for microwave
coagulation therapy. It closely follows the analysis found in Ref. 1. It computes the
temperature distribution in the tissue using the bioheat equation.
Model Definition
Figure 3-20 shows the antenna geometry. It consists of a thin coaxial cable with a
ring-shaped slot measuring 1 mm cut on the outer conductor 5 mm from the
short-circuited tip. For hygienic purposes, the antenna is enclosed in a sleeve (catheter)
made of PTFE (polytetrafluoroethylene). The following tables give the relevant
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